Rearrangement of penicillin

ABSTRACT

TREATMENT OF A PENICILLIN SULFOXIDE WITH A TRIPHENYL PHOSPHINE OR TRIALKYL PHOSPHITE RESULTS IN REARRANGEMENT TO A THIAZOLINE AZETIDINONE, THIS REARRANGEMENT PRODUCT CAN THEN BE CONVERTED TO A CEPHALOSPORIN OR TO A DIFFERENT PENICILLIN.

United States Patent O US. Cl. 260-2391 22 Claims ABSTRACT OF THEDISCLOSURE Treatment of a penicillin sulfoxide with a triphenylphosphine or trialkyl phosphite results in rearrangement to a thiazolineazetidinone. This rearrangement product can then be converted to acephalosporin or to a different penicillin.

CROSS-REFERENCE This application is a continuation-in-part of mycopending application Ser. No. 832,836, filed June 12, 1969.

BACKGROUND OF THE INVENTION The penicillins and cephalosporins arewell-known families of antibiotics, both of which are widely used in thetreatment of disease. Members of both families can be obtained byfermentation processes; however, there is a continuing search for waysto chemically modify existing members of the families and for syntheticor semi-synthetic routes to new and known compounds.

One such semi-synthetic route to cephalosporins in that described inMorin and Jackson US. Pat. 3,275,626. By means of the process theredescribed a penicillin sulfoxide is rearranged to a cephalosporin.Cephalosporins obtained by this process have a methyl group attached tothe 3-position of the ring and are valuable antibiotics.

SUMMARY I have now discovered another method for the rearrangement of apenicillin sulfoxide, this time to a thiazoline azetidinone, bytreatment with at least one equivalent of triphenyl phosphine or atrialkyl phosphite at a temperature within the range of 40 to 125 C.Upon treatment with a peracid and a carboxylic acid this rearrangementproduct is converted to a mixture of a desacetoxycephalosporin sulfoxideand a hydroxymethylpenicillin sulfoxide.

DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with my process apenicillin sulfoxide is treated with triphenyl phosphine or a trialkylphosphite at a temperature within the range of 40 to 125 C. andpreferably Within the range of 50 to 110 C. The trialkyl phosphiteemployed in the process is one in which each alkyl group contains fromone to four carbon atoms. Such lower alkyl phosphites are preferredbecause they are easy to separate from the product. The phosphitesthemselves are volatile compounds while the phosphates formed in thereaction are water soluble. Examples of suitable lower alkyl phosphitesinclude trimethyl phosphite, triethyl phosphite, tri-n-propyl phosphiteand tri-n-butyl phosphite. The preferred phosphites are trimethyl andtriethyl phosphite.

3,705,892 Patented Dec. 12, 1972 The penicillin sulfoxide startingmaterial may be prepared by any convenient method for preparingpenicillin sulfoxides such as the process described in US. Pat.3,197,466. The carboxyl group of the penicillin sulfoxide startingmaterial is preferably esterified to protect this group during therearrangement reaction. Penicillin esters are Well known to thoseskilled in the art. The preferred ester groups are those that may beeasily removed to regenerate the free acid. Typical of such groups arethe t-butyl, benzyl, methoxybenzyl, nitrobenzyl, benzhydryl,trichloroethyl and phenacyl groups.

Thus, suitable penicillin sulfoxides for my process are those having theformula R-ii-NH-CEOH wherein R is C -C alkyl, C -C cycloalkyl, or C -Calkenyl, optionally substituted with hydroxyl, mercapto, C -C alkoxy, C-C alkylthio, halo, or cyano; hydrogen; carboethoxy;

Q (in, Q is hydrogen, hydroxyl, mercapto, chloro, bromo,

fluoro, C -C alkyl, C -C alkoxy, C -C alkylthio, nitro, or cyano; X isoxygen, sulfur, or a carbon to carbon bond; Y is hydroxyl, mercapto,azido, or amino; m is an integer of 0-2; 12 is an integer of 1-2; R is-CH OZ,

R" is hydrogen, C -C alkyl, C -C t-alkyl, C -C t-alkenyl, C -Ct-alkynyl, benzyl, methoxybenzyl, nitrobenzyl, benzhydryl,phthalirnidomethyl, succinimidomethyl, phenacyl, or trichloroethyl; and

Z is hydrogen; C -C alkyl, C -C cycloalkyl, or

C C alkenyl, optionally substituted with hydroxyl, mercapto, C -Calkoxy, C -C alkylthio, or cyano; or phenyl or phenyl-C 0 alkyl,optionally substituted with hydroxyl, mercapto, chloro, fluoro, bromo, C-C alkyl, C -C alkoxy, C -C alkylthio, nitro, or cyano.

It is understood that hydroxyl, mercapto, and amino groups are protectedduring the reaction, all in accordance with procedures known in the art.For example, hydroxyl and mercapto groups are protected by the formationof an ester or thioester such as the formate, acetate, ortrifiuoroacetate. Amino groups are protected by substitution by aneasily removable group such as triphenylmethyl, t-butyloxycarbonyl,trichloroethoxycarbonyl, benzyloxycarbonyl, lower alkanoyl, benzoyl, orthe enamine from rnethyl acetoacetate. The protection of hydroxyl,mercapto, and amino groups is well known to those skilled in the art.The particular protecting group employed is not important to thisinvention.

Specific examples of R include benzyl, phenoxymethyl, 2phenoxyisopropyl, or azidobenzyl, benzyloxymethyl, c (Nbenzyloxycarbonylamino) benzyl, 4 mercaptobenzyl, methyl, cyclohexyl,methoxyethyl, methylthioethyl, n-hexyl, pentenyl, t-butyl, cyclopentyl,2-cyan0- propyl, a-hydroxybenzyl, m-chlorobenzyl, p-ethoxyphenoxymethyl,p-nitrophenoxyethyl, o-methylbenzyl, and p-hydroxyphenoxymethyl. Thefirst three are preferred groups. Specific examples of R" includemethyl, ethyl, t-butyl, 3-methyl-3-bntenyl, 3-methyl-3-butynyl, benzyl,p-methoxybenzyl, p-nitrobenzyl, phenacyl, and trichloroethyl. When R" ishydrogen, the carboxyl group is esterified by an alkyl group from thetrialkylphosphate, so that the product is an ester. The preferred R"groups are trichloroethyl and p-nitrobenzyl. Examples of Z includehydrogen, methyl, ethyl, hexyl, cyclohexyl, t-butyl, cyclopentyl,methoxyethyl, pentenyl, 3-cyanopentyl, phenyi, benzyl, 2-phenyl-ethyl,m-chlorophenyl, p-ethoxybenzyl, p-nitrophenyl, o-methylbenzyl, and2-(p-hydroxyphenyl) ethyl.

Typical starting materials for my rearrangement process are thefollowing penicillin sulfoxides:

Penicillin V sulfoxide Trichloroethyl ester of penicillin V sulfoxidep-Nitrobenzyl ester of penicillin G sulfoxide Methyl6-(m-chlorophenylacetamido)penam-3-carboxylate-l-oxide 3-hydroxymethyl-6- cyclohexylcarboxamido) penaml-oxide 3-acetoxymethyl-6-capramido penaml-oxide 3-butoxymethyl-6-(p-nitrophenoxyacetamido)penaml-oxide N-methylamide of penicillin Vsulfoxide 3-hydroxymethyl-6- mandelamido penaml-oxide 3benzyloxymethyl-G-acetamidopenam-I-oxide 3-benzoyloxymethyl-6-(phenoxyacetamido)penaml-oxide.

Those skilled in the penicillin art will recognize that R, R, R" and Zmay have other values equivalent to those named. The essential elementsof the starting material are the penam nucleus and the amido group inthe 6-position.

The thiazoline azetidinone rearrangement product obtained from myprocess is one having the formula wherein R and R have the valuesrecited above, and in addition, R may be C -C alkoxy. It is to beunderstood that when R is an ester group it may be converted to the freeacid.

With one exception to be described below, neither R nor R is changedduring the rearrangement reaction so that both have the same value inthe product as they had in the starting penicillin sulfoxide. Theseproducts are novel chemical compounds which can be converted intocephalosporins and 2-hydroxymethylpenicillins as will be described inmore detail below.

Upon treatment with an oxidizing agent as described hereinbelow theabove rearrangement product is converted to a mixture of adesacetoxycephalosporin sulfoxide and a Z-hydroxymethylpenicillinsulfoxide having the following formulas:

and

Once again, R and R remain unchanged and so have the values they had inthe original penicillin sulfoxide starting material. Occasionally theester group and hydroxyl group of the penicillin cyclize to a lactone.

Two types of oxidizing agents may be used in this process. The firsttype is a mixture of an organic carboxylic peracid and a carboxylic acidhaving a dissociation constant of at least 10- The second type is amixture of hydrogen peroxide and an acid having a dissociation constantof at least 10 Organic carboxylic peracids are well known to thoseskilled in the art and include m-chloroperbenzoic acid, peracetic acid,trifluoroperacetic acid, performic acid, and permaleic acid. The organiccarboxylic peracid may be added as such or may be generated in situ bythe use of at least an equivalent of hydrogen peroxide and a carboxylicacid. It is often desirable to use a large excess of the carboxylic acidas, for example, when acetic acid is used as the solvent. In carryingout this reaction with carboxylic peracids at least a catalytic amountof a carboxylic acid having a dissociation constant of at least 10 mustalso be used. The stronger the acid the more efifective it is as acatalyst. Catalytic quantities of as little as l to 2 percent or less ofthe acid are sufiicient. Acids that exhibit some catalytic activity inthis oxidation include acetic acid, formic acid, and trifluoroaceticacid.

The second class of oxidizing agent is a mixture of at least oneequivalent of hydrogen peroxide and an acid having a dissociationconstant of at least lO In some Ways this overlaps with the in situgeneration of a carboxylic peracid but also includes mixtures whereinless than an equivalent amount of the acid are employed. For example,only catalytic amounts of l to 2 percent of the acid are suificient.Larger amounts of the acid may be employed. The stronger the acid themore effective is the mixture. It is not known if the oxidation proceedsthrough a peracid which is continuously regenerated by the hydrogenperoxide present or whether hydrogen peroxide is the oxidizing agent andthe acid is acting as a catalyst for this oxidation. Acids which may beused in this manner with hydrogen peroxide include, for example, aceticacid, perchloric acid and trifiuoroacetic acid. The preferred oxidizingagents for this step of the process are perforrnic acid,trifluoroperacetic acid and m-chloroperbenzoic acid in the presence ofacetic or trifluoroacetic acid.

This oxidation-rearrangement step is conducted at a temperature withinthe range of about 20 to C. and preferably within the range of about 0to 50 C. The reaction is preferably conducted in an inert, organicsolvent such as benzene, tetrahydrofuran, acetonitrile, ordimethylformamide. In addition, an excess of an acid such as acetic acidor trifluoroacetic acid may be employed as the solvent. At least oneequivalent of oxidizing agent per mole of intermediate rearrangementproduct should be used and preferably a slight excess of from to percentof the oxidizing agent is employed. Larger excesses may be used butoffer no additional beneficial results.

My novel rearrangement process will be illustrated by the followingexamples.

EXAMPLE 1 A mixture of 4.97 g. of the trichloroethyl ester of penicillinV sulfoxide and 1.86 g. of trimethyl phosphite in 120 ml. of ethylacetate was heated under reflux for two days. The ethyl acetate wasremoved in vacuo and the residue was washed with cold Skellysolve B andrecrystallized three times from 2B ethanol to yield 1 g. of productwhich was shown by infrared and nuclear magnetic resonance spectroscopyto have the following structure:

Analysis.Calculated for C H N O Cl S (percent): C, 46.61; H, 3.69; N,6.04. Found (percent): C, 46.85; H, 3.64; N, 6.14.

EXAMPLE 2 Example 1 was repeated using 120 ml. of chloroform instead ofethyl acetate and heating the mixture under reflux for five days.Evaporation of the chloroform left a crystalline material which wasrecrystallized from ethanol. Thin-layer chromatography showed theproduct to contain two spots. The crystals and the residue from theevaporation of the ethanol filtrate were combined and chromatographedover silica gel using 3:7 ethyl acetate/ benzene as eluent. There wasobtained 2.6 g. of a product having a melting point of 142 C. and whichwas shown by analysis and nuclear magnetic reasonance spectroscopy to bethe same as the product from Example 1. In addition 750 mg. of startingmaterial was recovered.

EXAMPLE 3 The procedure of Example 1 was repeated employingtetrahydrofuran as solvent and heating under reflux for four days.Evaporation of the tetrahydrofuran left a white crystalline productwhich was washed with cold Skellysolve B and recrystallized fromethanol. There was obtained 2.82 g. of product melting at 135-137 C. andshowing only one spot on thin-layer chromatography. This product wasconfirmed to be identical to the product from Example 1 by elementalanalysis and nuclear magnetic reasonance spectroscopy.

EXAMPLE 4 A mixture of 10 g. of the trichloroethyl ester of penicillin Vsulfoxide and 2 ml. of triethyl phosphite in 200 ml. of benzene washeated under reflux for 24 hours. The solvent was removed under vacuumand the residue was triturated and washed with cold Skellysolve B, thenrecrystallized from ether as needles melting at 133 C. The yield was 6g. Nuclear magnetic reasonance spectroscopy confirmed the product to bethe same as that obtained from Example 1.

EXAMPLE 5 A mixture of 4.96 g. of the trichloroethyl ester of penicillinV sulfoxide and 2.67 g. of triphenyl phosphine in benzene was heatedunder reflux for 48 hours. The reaction mixture was cooled, methyliodide was added, and the solution allowed to stand overnight. Themixture was filtered and the filtrate was evaporated and the residuerecrystallized from methanol to yield 1 g. of crystalline 6 productwhich was shown by nuclear magnetic resonance spectroscopy to be thesame as the product from Example 1.

EXAMPLE 6- A mixture of 1.36 g. of the trichloroethyl ester ofpenicillin G sulfoxide and 1 ml. of trimethyl phosphite in 50 ml. ofbenzene was heated under reflux for 36 hours. The solution was washedwell with water, the solvent was removed under vaccum leaving a whitesolid which was recrystallized from methanol to give 985 mg. of whiteneedles melting at 145 C. This product Was confirmed by nuclear magneticresonance spectroscopy to have the following structure.

Analysis.-Calculated for C H N O Cl S (percent): C, 48.27; H, 3.83; N,6.25; Cl, 23.75; S, 7.16. Found (percent): C, 48.51; H, 3.99; N, 6.48;Cl, 23.54; S, 7.30.

EXAMPLE 7 A mixture of 31 g. of the methyl ester of penicillin Vsulfoxide and 20 ml. of triethyl phosphite in 600 ml. of benzene washeated under reflux using a water separator for 24 hours. Removal of thesolvent under vacuum left a yellow oil which was dissolved in methanoland treated with charcoal. Evaporation of the methanol left a paleyellow oil which was shown by nuclear magnetic reasonance spectroscopyto be the methyl ester corresponding to the product of Example 1,containing some triethyl phosphate.

EXAMPLE 8 A mixture of g. of the p-nitrobenzyl ester of penicillin Vsulfoxide and 50 ml. of trimethyl phosphite in l l. of ethyl acetate and40 ml. of tetrahydrofuran was heated under reflux for two days. Thesolvent was removed under vacuum, the residue triturated with benzeneand the mixture filtered to yield 20 g. of starting material. Thebenzene was evaporated under vacuum and the residue was crystallizedfrom methanol to yield 50 g. of product which was confirmed by spectralanalysis to be the p-nitrobenzyl ester corresponding to the product ofExample 1.

EXAMPLE 9 A solution of 270 mg. of3-acetoxymethyl-6-phenoxyacetamidopenam sulfoxide and 0.5 ml. oftrimethyl phosphite in 50 ml. of benzene was heated under reflux for 48hours. The reaction mixture was washed with water and the solvent wasevaporated under vacuum to yield a yellow oil. Thin-layer chromatographyshowed one main spot. The product was purified by chromatography oversilica in a benzene solvent, eluting with 3:7 ethyl acetate/ benzene.There was obtained 121 mg. of a colorless oil which was shown by nuclearmagnetic resonance spectroscopy to be the acetoxymethyl derivativecorresponding to the ester obtained in Example 1.

EXAMPLE 10 A solution of 420 mg. of3-hydroxymethyl-6-phenoxyacetamidopenam sulfoxide and 0.5 ml. oftrimethyl phosphite in 50 ml. of benzene was heated under reflux for 24hours. The reaction mixture was washed with Water, dried, and thesolvent removed under vacuum to yield 400 mg. of a colorless oil. Thisproduct was shown by nuclear magnetic resonance spectroscopy to be thehydroxymethyl derivative corresponding to the ester of Example 1.

7 EXAMPLE 11 A solution of 137 mg. of the N-t-butylamide of penicillin Vsulfoxide and 0.5 ml. of trimethyl phosphite in 50 ml. of dioxane washeated under reflux for 25 hours. The dioxane was evaporated undervacuum, the residue was dissolved in ethyl acetate and the solution waswashed with water, dried, and the ethyl acetate removed under vacuum toyield 170 mg. of a colorless oil. Nuclear magnetic resonancespectroscopy showed this product to be the butylamide corresponding tothe ester product of Example 1.

EXAMPLE 12 A solution of 33 g. of trichloroethyl 6-(a,x'dimethylphenoxyacetamido)penam-3-carboxylate sulfoxide and ml. oftrimethyl phosphite in 250 ml. of benzene was heated under reflux untilthin-layer chromatography showed most of the starting material hadreacted (about two days). The benzene solution was washed several timeswith water, dried, and the benzene evaporated. The residue wascrystallized from methanol to give 5.5 g. of product melting at 145 C.This product was shown by nuclear magnetic resonance spectroscopy tohave the following structure.

suing-0Q Analysis.-Calculated for C I-I N O CI S (percent): C, 48.83; H,4.30; N, 5.70; Cl, 21.62; S, 6.52. Found (percent): C, 49.05; H, 4.59;N, 5.94; Cl, 21.82; S, 6.36.

EXAMPLE 14 To a Warm solution of 2.48 g. (0.005 mole) of penicillin Vsulfoxide trichloroethyl ester in ml. of dry benzene were added 75 ml.of carbon tetrachloride and 744 mg. of trimethyl phosphite. This mixturewas heated under refiux for 22 hours. Thin-layer chromatography showedthe product to be one spot material with no starting material present.The solvents were removed in vacuo and the residue recrystallized fromethanol. There was obtained v 2.1 g. of white, feathery crystals meltingat 133 C. Elemental analysis and nuclear magnetic resonance spectroscopyconfirmed the product to be identical to the product from Example 1.

EXAMPLE 15 To a suspension of 5.6 g. of 6-aminopenicillanic acid (6-APA)in 150 ml. of methylene chloride was added 3.4 ml. of trimethylamine.The solution was stirred at 0 C. for 45 minutes and 2 ml. of aceticformic anhydride was added. The solution was stirred for 1 hour at 0 C.and another hour at room temperature. Filtration of the solution removed1.58 g. of unreacted 6-APA. The filtrate was concentrated in vacuo andthe residue dissolved in ethyl acetate. Water was added and the pHadjusted to 2.5 with dilute hydrochloric acid. The ethyl acetatesolution was removed and washed with sodium bicarbonate solution.

8 The sodium bicarbonate solution was acidified to pH 3 and extractedwith ethyl acetate. The ethyl acetate extract was dried over magnesiumsulfate and the solvent removed in vacuo to give a bulf foam. NMR and IRidentified the product as N-formylpenicillin. To a suspension of 1 g. ofN-formylpenicillin in ether was added an ethereal solution ofdiazomethane until a residual yellow color remained. The solvent wasremoved in vacuo, the residue dissolved in chloroform, and treated with1 equivalent of m-chloroperbenzoic acid at room temperature for 1 hour.The solution was washed with sodium bisulfite solution and then sodiumbicarbonate solution, dried, and the solvent removed in vacuo to give135 mg. of a foam which was shown by NMR to be the methyl ester ofN-formylpenicillin sulfoxide. A solution of 130 mg. of the sulfoxide in30 ml. of dry benzene containing 3 drops of trimethyl phosphite washeated under reflux for 24 hours. The solution was washed well withwater and the solvent removed in vacuo to give 46 mg. of product as apale yellow oil. NMR showed it to be in the thiazoline having thestructure.

H t S |JHi H 3H3 0=C-N-CHC=CH3 EXAMPLE 16 A suspension of 10.8 g. of-6-APA in 400 ml. of methylene chloride containing 10.1 g. oftriethylamine was stirred at room temperature for 3 hours. Filtrationremoved 2.5 g. of undissolved 6-APA. The filtrate was cooled to 7 8 C.and a solution of 6.8 g. of ethyloxalyl chloride in methylene chloridewas added dropwise. After addition was complete the temperture wasmaintained at 40 C. for 2 hours and at 0 C. for 16 hours. The solutionwas evaporated in vacuo and the residue dissolved in equal volumes ofethyl acetate and water. The pH was adjusted to 2.5 and the ethylacetate layer removed, washed several times with water, dried overmagnesium sulfate, and the solvent removed in vacuo to leave 7.5 g. ofN- ethyloxalylpenicillin. To a solution of 798 mg. ofN-ethyloxalylpenicillin in 20 m1. of ether was added an etherealsolution of diazomethane until a yellow color remained. The solution wasthen stirred at room temperature for /2 hour and the solvent removed invacuo to leave 780 mg. of a yellow foam which was shown by NMR to be themethyl ester. This ester was dissolved in ml. of methylene chloride and200 mg. of m-chloroperbenzoic acid was added. The solution was stirredat room temperature for /2 hour and another 50 mg. of the peracid wasadded. After an additional /2 hour the solution was washed with sodiumbisulfate solution followed by sodium bicarbonate solution, dried, andevaporated in vacuo to leave 700 mg. of white foam shown by NMR to bethe methyl ester of N-ethyloxalylpenicillin sulfoxide. A solution of 100mg. of the sulfoxide and V2 ml. of trimethylphosphite in 100 ml. ofbenzene was heated under reflux for 20 hours. The solution was washedwell with water, dried over magnesium sulfate, and evaporated in vacuoto leave 89 mg. of white crystals shown by NMR to be the thiazolinehaving the formula 9 EXAMPLE 17 A solution of 1 g. of the p-nitrobenzylester of chloroacetylpenicillin sulfoxide and 1 ml. oftrimethylphosphite in 50 ml. of dioxane was heated under reflux for 16hours. The solvent was removed in vacuo and the residue dissolved inethyl acetate. The ethyl acetate solution was washed well with water andthe ethyl acetate removed in vacuo to give 850 mg. of a yellow oilidentified as the thiazoline having the structure I I CH-CH CH;

.LO.CH.@ NO.

EXAMPLE 18 A solution of 3.66 g. of penicillin V sulfoxide in 50 ml. oftrimethyl phosphite was heated on a steam bath for 12 hours. The mixturewas evaporated in vacuo, the residue dissolved in ethyl acetate, theethyl acetate washed well with water, dried, and the solvent evaporatedin vacuo to leave 2.65 g. of a colorless, neutral oil. NMR showed theproduct to be the thiazoline having the structure Thus, the freecarboxyl group was converted to the methyl ester by the trimethylphosphite.

The above examples illustrate my rearrangement process using differentphosphorus reagents with a number of penicillins 'bearing differentsubstituents in the 3- and 6-positions. These examples demonstrate thatthe process is a general one and is independent of the substituents onthe penicillin nucleus. Those skilled in the penicillin art willrecognize that other penicillins or penicillin derivatives that containthe penam nucleus may be employed in the process in an equivalentmanner.

As noted earlier, I have discovered one case in which R in the startingpenicillin sulfoxide does not survive the rearrangement reaction so thata different group is present in the thiazoline azetidinone. Thus, when Rin the penicillin sulfoxide is two products are recovered from thereaction. They have the following formulas:

wherein W is an al-kyl group from the trialkyl phosphite. Thus, R in thegeneric formula of the thiazoline azetidinone may be C -C alkoxy. Thesecond product does not fit the generic formula. The preparation ofthese two compounds will be illustrated by the following example.

EXAMPLE 19 A suspension of 20 g. of 6-APA in 100 ml. of methylenechloride containing 20 ml. of triethylamine was stirred at roomtemperature for /2 hour, filtered to remove undissolved 6-APA, and 18 g.of p-toluenesulfonylisocyanate was added slowly at 0 C. The solution wasstirred at 10 C. for 1 hour, washed with dilute hydrochloric acid, driedover magnesium sulfate, and evaporated in vacuo to leave 40 g. oftosylureidopenicillin as a white foam. A solution of 20 g. of this foamin 200 ml. of methylene chloride was treated with an ethereal solutionof diazomethane until a yellow color persisted. The solvent was removedin vacuo to leave a white foam which was dissolved in 200 ml. ofchloroform and 10.5 g. of m.-chloroperbenzoic acid was added. Thesolution was stirred at room temperature for 1 hour then washed withsodium bisulfite solution and sodium bicarbonate solution. Thechloroform solution was dried over magnesium sulfate and the solventremoved in vacuo to give a white foam which was purified bychromatography on silica gel in benzene-ethyl acetate to gixe 10 g. of aproduct shown by NMR to be the methyl ester ofN-methylp-toluenesulfonyl-ureidopenicillin sulfoxide. A solution of 1 g.of the sulfoxide and 1 ml. of trimethyl phosphite in 50 ml. of benzenewas heated under reflux for 16 hours. The solution was washed well withwater, dried over magnesium sulfate, and the solvent removed in vacuo togive a white foam. This form was shown to be a mixture of the twocompounds shown above wherein W is methyl and R is methoxycarbonyl.There was also some N-methyltoluenesulfonamide present. Extensivechromatography gave the 2-methoxythiazoline and the thiazolidinone aspure oils.

The conversion of the intermediate rearrangement products obtained inthe above examples to desacetoxycephalosporins andhydroxymethylpenicillins will be illustrated by the following examples.

EXAMPLE 20 A mixture of 9.26 g. of the product from Example 1, 5 g. ofm-chloroperbenzoic acid and 20 ml. of tlllflllOlO- acetic acid in 500ml. of benzene was stirred at 10 C. until a negative starch-iodide testwas obtained (about one and one-half hours), then an additional hour atroom temperature. The solution was washed twice With sodium carbonatesolution, dried over magnesium sulfate and the solvent was removed invacuo to leave a yellow residue.

The addition of ether of this residue resulted in the precipitation of2.2 g. of unreacted starting material. Evaporation of the ether solutionagain gave a yellow residue. The infrared spectrum of this residueshowed strong adsorption at 1800 cmr The product was chromatographedover silica eluting with ethyl acetate/benzene. The first 500 ml. ofeluate was discarded and the following fractions were then collected.

Fraction A 2.5 g.

Fraction B 1.56 g.

Fraction C 0.374 g.

Fraction D 0.83 g.

Fraction E 0.45 g.

Fraction F 1.42 g. (from 1 l. of

ethyl acetate).

Fraction G 1.50 g. (from 1 l. of

acetone).

Fractions C, D, E, F and G were recombined and rechromatographed oversilica eluting with 25 percent actone in chloroform and graduallyincreasing to 33 percent ace- Fractions H and G were crystallized frommethanol to yield a crystalline compound containing no chlorine normethylene group of the trichloroethyl group. By means of massspectrometry and nuclear magnetic resonance spectrometry the structureof this product was determined to be the following.

Fractions B, C, D, and B were recombined and rechromatographed on silicaeluting with 2:1 benzene/ethyl acetate. In this manner there wereobtained 430 mg. of Compound A and 238 mg. of Compound B. Nuclearmagnetic resonance showed Compound A to be the desired trichloroethylester of 2 hydroxymethylpenicillin V sulfoxide while Compound B wasshown to be the desired trichloroethyl ester of desacetoxycephalosporinV sulfoxide.

EXAMPLE 21 A solution of 4.67 g. of the p-nitrobenzyl ester productprepared as in Example 8, 4.35 g. of m-chloroperbenzoic acid and 6 dropsof trifluoroacetic acid in dimethylformamide was kept at C. forapproximately 48 hours. The solvent was removed in vacuo, the residuewas dissolved in ethyl acetate, the ethyl acetate solution washed withsodium carbonate solution, dried over magnesium sulfate, and evaporatedto give 3.6 g. of product. This product was chromatographed over silicaeluting with 3:7 ethyl acetate/benzene. In this manner there wereobtained 125 mg. of the p-nitrobenzyl ester of desacetoxycephalosporin Vsulfoxide and 200 mg. of the p-nitrobenzyl ester of 2-hydroxymethylpenicillin V sulfoxide.

EXAMPLE 22 A solution of 4.63 g. of the trichloroethyl ester obtained asin Example 1, 4.35 g. of m-chloroperbenzoic acid and 3 drops oftrifluoroacetic acid in 200 ml. of tetrahydrofuran was stirred at 0 C.until a negative starch-iodide test was obtained (about 4 hours). Thesolvent was removed in vacuo, the residue was dissolved in ethyl ace-Mg. Fraction 1 1170 Fraction 2 550 Fraction 3 340 Fraction 4 180Fraction 5 200 Fraction 6 109* Fraction 7 230 Fraction 3 was shown bynuclear magnetic resonance and mass spectrometry to be thetrichloroethyl ester of Z-hydroxymethylpenicillin V sulfoxide. Fractions4 through 7 were shown to be the trichloroethyl ester ofdesacetoxycephalosporin V sulfoxide, both the ocand fl-isomers beingobtained. Recrystallization of these fractions resulted in a producthaving a melting point of 185 to 186 C.

It can be seen that treatment of the thiazoline product with a peracidresults in the formation of a hydroxymethylpenicillin sulfoxide or adesacetoxycephalosporin sulfoxide. In addition, the correspondingsulfides and sulfones are sometimes formed. The hydroxymethylpenicillinsometimes is converted to the corresponding lactone, while occasionallythe original penicillin is also formed in small amounts. There is thusoffered a novel method for the preparation of desacetoxycephalosporinsand functionalized methylpenicillins.

Treatment of the thiazoline azetidinone with a base under mildconditions results in the isomerization of the side chain double bond togive a product having the formula R l N s lH-(JH CH: o=c--1iIo=( 3CH;

wherein R and R have the values assigned above. This shift of the doublebond occurs in the presence of a base having a dissociation constantgreater than about 10- at a temperature within the range of 050 C., andpreferably within the range of 20 -30 C., for a time of not more than 30minutes. If the reaction is allowed to proceed longer than about 30minutes further reaction occurs leading to lay-products. The base mayserve as the solvent for this reaction or an inert solvent such asmethanol, ethanol, tetrahydrofuran, dioxane, or dimethylformamide can beused.

The base to be used in the isomerization is an organic or inorganic basehaving a dissociation constant greater than about 10-. Examples of suchbases include sodium hydroxide, sodium carbonate, sodium methoxide,potassium methoxide, trimethylamine, N,N-dimethylaniline, pyridine,diethylamine, methylamine, piperidine, and ammonia. Approximately oneequivalent of base per mole of starting thiazoline azetidinone should beused.

The isomerization reaction will be further illustrated by the followingexample.

EXAMPLE 23 A solution of 150 mg. of the product from Example 4 in 20 ml.of triethylamine was allowed to stand at room temperature for 16 hours.The triethylamine was removed in vacuo leaving mg. of an oil. Thin-layerchromatography showed one spot running slightly ahead of startingmaterial. The infrared spectrum showed the presence of the B-lactam andester groups, while the nuclear magnetic resonance spectrum showed twomethyl groups attached to a double bond, thus confirming the presence ofthe product having the formula The ease with whichthis isomerizationtakes place is illustrated by the following example in which theoriginal rearrangement reaction was conducted under apparently mildlybasic conditions to give the same product as was obtained in Example 18rather than the expected isomer having the double bond in a terminalposition.

EXAMPLE 24 A mixture of 4.97 g. of penicillin V sulfoxide trichloroethylester and 1.86 g. of trirnethyl phosphite in 25:75 formamide/benzene washeated under reflux over the weekend. Evaporation of the solvents invacuo left a dark oil which was taken up in ethyl acetate. Thin-layerchromatography showed very little starting material. The ethyl acetatesolution was washed several times with water, the ethyl acetate wasevaporated, and the residue was chromatographed over silica gel using3:7 ethyl acetate/ benzene as eluent. There was obtained 3.8 g. of anoil which was shown by its nuclear magnetic resonance spectrum to be thesame as the product from Example 18. There was also obtained 846 mg. ofstarting material. It is believed that this isomer was obtained becauseof the presence of some amine in the formamide used as solvent.

These thiazoline azetidinones having the side-chain double bond in the ae-position are useful in the treatment of plant diseases. For example,the ester from Example 23 and the corresponding acid are extremelyactive against Fusarium Root Rot. This activity was detected by applyingthe compound at a broadcast rate of 40 pounds per acre toFusarium-infested soil and then planted Bountiful variety bean seeds inthe soil. After 14 days the bean plants were found to be free of thedisease.

In addition, these compounds are useful as antibiotics. The ester fromExample 23 is active against Botrytz's cinerea at a concentration of 100mcg./ml. as determined by an agar dilution test method described bySteers and Foltz in Antibiotics and Chemotherapy 9, p. 307 (1959).

I claim:

1. A method for the preparation of a penicillin rearrangement producthaving the formula H-ASH CH; O=Jl-NCH =CH:

h! which comprises treating a penicillin sulfoxide having the formulaDenna-brou h- Q is hydrogen, hydroxyl, mercapto, chloro, bromo, fluoro,C -C alkyl, C -C alkoxy, C -C alkylthio, nitro, or cyano;

X is oxygen, sulfur, or a carbon to carbon bond;

Y is hydroxyl, mercapto, azido, or amino;

m is an integer of 0-2;

n is an integer of 1-2;

R is CH OZ,

R" is hydrogen, C -C alkyl, C -C t-alkyl, C -C t-alkenyl, C -Ct-alkynyl, benzyl, methoxybenzyl, nitrobenzyl, benzhydryl,phthalimidomethyl, succinimidomethyl, phenacyl, or trichloroethyl; and

Z is hydrogen; C -C alkyl, C -C cycloalkyl, or

C -C alkenyl, optionally substituted with hydroxyl, mercapto, C -Calkoxy, C -C alkylthio, or cyano; or phenyl or phenyl-C 43 alkyl,optionally substituted with hydroxy, mercapto, chloro, fiuoro, bromo, C-C alkyl, C -C alkoxy, C -C alkylthio, nitro, or cyano.

2. A method as in claim 1 wherein the penicillin sulfoxide is treatedwith trimethyl phosphite at a temperature within the range of 50 to C.

3. A method as in claim 1 wherein the penicillin sulfoxide is treatedwith triethyl phosphite at a temperature within the range of 50 to 110C.

4. A compound having the formula wherein R is C -C alkyl, C -Ccycloalkyl, or C -C alkenyl, optionally substituted with hydroxyl,mercapto,

C -C alkoxy, C -C alkylthio, halo, or cyano; hydrogen; carboethoxy; C -Calkoxy;

Q is hydrogen, hydroxyl, mercapto, chloro, bromo, fiuoro, C -C alkyl, C-C alkoxy, C -C alkylthio, nitro, or cyano;

X is oxygen, sulfur, or a carbon to carbon bond;

Y is hydroxyl, mercapto, azido, or amino;

m is an integer of 0-2;

n is an integer of 1-2;

R is CH OZ,

R" is hydrogen, C -C alkyl, C C t-alkyl, C -C t-alkenyl, C -C t-alkenyl,benzyl, methoxybenzyl, nitrobenzyl, benzhydryl, phthalimidomethyl,succinimidomethyl, phenacyl, or trichloroethyl; and

Z is hydrogen; C -C alkyl, C -C cycloalkyl, or

C -C alkenyl, optionally substituted with hydroxyl mercapto, C -Calkoxy, C -C alkylthio, or cyano; or phenyl or phenyl-C -C alkyl,optionally substituted with hydroxyl, mercapto, chloro, fiuoro, fluoro,bromo, C -C alkyl, C C3 alkoxy, C -C alkylthio, nitro, or cyano.

5. A compound as in claim 4 wherein R is phenoxymethyl and R is 6. Acompoundas in claim 5 wherein R" is trichloroethyl.

7. A compound as in claim 5 wherein R" is p-methoxybenzyl.

8. A compound as in claim 5 wherein R" is p-nitrobenzyl.

9. A compound as in claim 4 wherein R is benzyl and R is o H -COR" 10. Acompound as in claim 9 wherein R" is trichloroethyl.

11. A compound as in claim 9 wherein R" is p-methoxy benzyl.

12. A compound as in claim 9 wherein R" is a-nitrobenzyl.

13. A compound as in claim 4 wherein R is 2-phenoxyisopropyl and R is14. A compound as in claim 13 wherein R" is trichloroethyl.

15. A compound as in claim 13 wherein R" is p-methoxybenzyl.

16. A compound as in claim 13 wherein R" is p-nitrobenzyl.

17. A compound having the formula wherein R is C -C alkyl, C -Ccycloalkyl, or C -C alkenyl, optionally substituted with hydroxyl,mercapto, C -C alkoxy, C -C alkylbhio, halo, hydrogen; carboethoxy, C -Calkoxy;

Q- Q i CH; QM- Q.

Q is hydrogen, hydroxyl, mercapto, chloro, hromo,

fluoro, C -C alkyl, C -C alkoxy, C -C alkyltbio, nitro, or cyano;

X is oxygen, sulfur, or a carbon to carbon bond;

Y is hydroxyl, mercapto, azido, or amino;

m is an integer of 0-2;

n is an integer of l-2;

or cyano;

- 1 6 R is CH OZ,

o CHzO ii z o -iiNHz 0 ll --C0R",

to a desacetoxycephalosporin sulfoxide and a Z-hydroxymethylpenicillinsulfoxide having the formulas which comprises treating the thiazolinewithat least one equivalent of a carboxylic peracid containing at leasta catalytic amount of a carboxylic acid having a dissociation constantof at least 10? or a mixture of hydrogen peroxide and an acid having adissociation constant of at least 10- at a temperature within the rangeof 20 C., wherein in the formulas R is C -C allcyl, C -C cycloalkyl, orC -C alkenyl, optionally substituted with hydroxyl, mercapto, C -Calkoxy, C -C alkylthio, halo, or cyano; hydrogen; carboethoxy; C -Calkoxy;

Q CHI

